Saturday, 1 August 2015

Organic Chemistry - Test 1

This test is on organic chemistry. You may like to revise the chapter on alkanes and alkenes, as well as the chapter on alcohols, carboxylic acids, esters and macromolecules first before attempting the question. 

The total score for this test is 10 marks. You should complete the test in 10 minutes.

Section A: Multiple Choice (3 marks)
1) When one mole of octane (C8H18) is cracked, it produces one mole of butane and one mole of compound X.

Determine compound X.

A. propane
B. propene
C. butane
D. butene

2) 20 cm3 of hydrocarbon Y was completely burnt in 200 cm3 of oxygen (both volumes measured at room temperature and pressure). The residual gas was then cooled to room temperature and pressure, and the volume was found to be 150 cm3. When this gas was passed through aqueous sodium hydroxide, the volume decreased by 80 cm3.

Which of the following could X be?

A. propane
B. propene
C. butane
D. butene

3) Ethanol reacts with hot acidified potassium manganate (VII) to form compound B. 

Which of the following is a property of compound B?
A. Compound B reacts with sodium carbonate to give carbon dioxide
B. Compound B reacts with sodium to give hydrogen 
C. Compound B undergoes esterification with an alcohol.
D. Compound B decolorizes aqueous bromine

Section B: Open- ended questions (6 marks)
1) 100g of ethene polymerizes to form 80 g of poly(ethene). Determine the percentage yield of poly(ethene). 
[1 mark]

2) Describe a simple test to distinguish between hexane and hexene. 
[2 marks]

3) A sweet smelling compound X is formed when ethanol reacts with methanoic acid in the presence of a catalyst.
i) Name the catalyst. 
ii) Draw the structure of compound X.
iii) Name compound X.
[4 marks]

Section A:
1) D
2) C
3) D

Section B:
1) 80%
2) Add aqueous bromine to each sample. Hexene will decolorize reddish brown bromine, but hexane will not decolorize reddish brown bromine.
3)i) concentrated sulfuric acid

iii) methyl ethanoate

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